Abstract

Both Antarctic and Arctic sympagic meiofauna investigated in this study included taxa new to sea ice. Diversity, abundance and biomass of metazoan meiofauna were significantly higher in a perennially than in a seasonally ice-covered Antarctic region. Brackish meltponds on Arctic sea ice hosted various proto- and metazoans. Stable isotope and fatty acid analyses combined with grazing and predation experiments showed that most metazoan meiofauna prey on ciliates and some even on metazoans. Many of them supplement their diets with algae, bacteria and detritus. A few meiofauna taxa are mainly herbivorous, but can additionally prey on ciliates or nauplii. Ingestion rates were influenced by food density (functional response) and predator density (competition). Grazing rates and the derived grazing impact of the meiofauna community were generally low. Predation rates, in contrast, were very high in some taxa, and the derived predation impact of the meiofauna community was accordingly high.